Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!uc!cs.umn.edu!ux.acs!hopper
From: hopper@ux.acs.umn.edu (hopper)
Newsgroups: comp.std.c++
Subject: Re: Packing, Ordering, and Rearranging
Message-ID: <2311@ux.acs.umn.edu>
Date: 1 Oct 90 01:05:43 GMT
References: <1407@lupine.NCD.COM> <2218@ux.acs.umn.edu> <57467@microsoft.UUCP> <1990Sep21.130531.7437@zorch.SF-Bay.ORG> <57650@microsoft.UUCP> <57681@microsoft.UUCP>
Reply-To: hopper@ux.acs.umn.edu (Eric Hopper)
Followup-To: <57681@microsoft.UUCP>
Organization: Omnifarious Software
Lines: 51

In article <57681@microsoft.UUCP> jimad@microsoft.UUCP (Jim ADCOCK) writes:
  Stuff deleted
>Thank you.  I think the suggestion we gravitated towards it that people
>who need to bit-twiddle can do so within the confines of an :
>
>extern "C"
>{
>    ....
>}
>
  Stuff deleted
>
>My claim is that the needs of "C++" "object-oriented" programming and "C"
>"bit-twiddling" will continue to diverge in the future, and we need to 
>separate these two needs.  Extern "C" would serve to tell compilers which
>set of needs are being met.
>
>In an extern "C" section, ANSI-C constraints would be met for ANSI-C constructs.
>Outside of an extern "C" sections, those constraints might not be applicable.

	I don't think that this will be the case. As more and more programs
are written in C++ that there will be more of a demand for 'bit-twiddling',
particularily if operating systems and the like are written in it.

	I don't think structure declarations that demand precise control
over placement of the bits within memory should be relegated to a patch-up
contruct like 'extern "C" {', they should be part of C++.

	I also think that the default method of member ordering should be
changed, it would cause confusion, and may make older code harder to port.
So I think that a 'packed' keyword ought to be added to the C++ language.

	I think Kent made a very good point earlier when he said that
currently popular languages all allow you to have a fair amount of precise
control over the machine beneath the language. If C++ turns into a 'school'
language in which you are not allowed control over such things as structure
member placement I think we'll see a loss of popularity, and portability.

Have fun,
UUCP: rutgers!umn-cs!ux.acs.umn.edu!hopper   (Eric Hopper)
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